How do you know if an older person lacks capacity?

The American Bar Association (ABA) Commission on Law and Aging and the American Psychological Association have prepared a booklet entitled Assessment of Older Adults With Diminished Capacity: A Handbook for Lawyers.

The Executive Summary explains that

With the coming demographic avalanche of Boomers reaching their 60s and the over-80 population swelling, lawyers face a growing challenge: older clients with problems in decision-making capacity. While most older adults will not have impaired capacity, some will. Clear and relatively obvious dementias will impair capacity, and the prevalence of such dementias increases with age. But what about older adults with an early stage of dementia or with mild central nervous system damage? Such clients may have subtle decisional problems and questionable judgments troubling to a lawyer. This handbook offers a conceptual framework and practice tips for addressing problems of client capacity, in some cases with help from a clinician.